1. Field of the Invention
This invention relates to the manufacture of tetrahydrofuran and 1,4-butanediol. In one aspect, the invention relates to the catalytic hydrogenation of oxygenated C.sub.4 hydrocarbons, such as maleic anhydride, while in another aspect, the invention relates to the use of ruthenium-containing hydrogenation catalysts.
2. Description of the Prior Art
The art is replete with processes for manufacturing tetrahydrofuran and 1,4-butanediol from oxygenated C.sub.4 hydrocarbons. A recent example is U.S. Pat. No. 4,155,919 which teaches a single-stage process for converting maleic anhydride into 1,4-butanediol and/or tetrahydrofuran by contacting the maleic anhydride with hydrogen at specified conditions in the presence of a catalyst containing nickel, molybdenum and/or tungsten, and optionally zirconium and/or niobium. Reaction conditions include a temperature from 170.degree.-215.degree. C. and a pressure of from 125-200 bars. Other known processes are cited in that teaching over columns 1-4. Still other processes are known and include U.S. Pat. Nos. 3,113,138, 3,957,827 and 3,370,067. While all of these processes are useful for their intended purpose, all are subject to improvement. Two disadvantages common to many of these processes are the need to use high pressures, e.g. in excess of 1500 psi, and generally unsatisfactory product yield.